The present disclosure relates to a method and system of inertia friction welding together parts.
Friction welding can be used to join similar and dissimilar metals in a short period of time compared to more conventional welding methods. Inertia friction welding is a variation of friction welding in which the energy required to make the weld is supplied primarily by stored rotational kinetic energy of the welding machine.
During inertia friction welding, material from the parts is displaced or “upset” which results in a reduction of the combined length of the welded parts. Thus, the finished product length is the sum of the length of the parts before the inertia friction welding process minus the effect of the upset experienced by the parts during the inertia friction welding process. Upset, and thus final product length, are subject to unpredictable variations and need to be controlled in inertia welding.
Profile based techniques for upset control have previously been used. Pending patent application of Lovin et al, Ser. No. 10/924,633, filed Aug. 24, 2004, controls upset by dynamically modifying the applied spindle motor torque during the deceleration to maintain an upset versus spindle velocity profile duplicating the upset of a previous test weld. This technique has been termed “torque modulated upset control” for those versed in the art. U.S. Pat. No. 4,757,932 Benn, et al controls upset by dynamically modifying the applied axial pressure during the deceleration to maintain an upset versus spindle velocity profile duplicating the upset of a previous test weld. This technique has been termed “pressure (or load) modulated upset control” for those versed in the art. However, Benn, et al and Lovin, et al, make no provisions for targeting either upset or final part length in inertia friction welding. These upset control techniques only reduce overall upset variability by precisely duplicating the upset dictated by a previous profile weld.
Techniques for final welded part length control and/or upset targeting in inertia welds have been used. U.S. Pat. No. 3,998,373 Jones, et al modified weld speed based on a preweld measurement of part dimensions attempting final welded part length control. If more upset is needed because the combined preweld length of the work parts is greater than nominal, the starting weld speed is increased. Conversely, if less upset is needed because the combined preweld length of the work parts is less than nominal, the starting weld speed is decreased. However, once the inertia weld cycle is initiated, upset is still an uncontrolled result of the weld process, and therefore the accuracy of the final part length is still limited to the variation in upset expected.